Organising kataras/go-fs. No api changes for these changes don't worry. See previous commit's description for more info.

Former-commit-id: 8af960e5e4e5f7c8816140ac912328b9c524370b

compression.go

@@ -0,0 +1,70 @@
+package iris
+
+import (
+	"io"
+	"sync"
+
+	"github.com/klauspost/compress/gzip"
+)
+
+// compressionPool is a wrapper of sync.Pool, to initialize a new compression writer pool
+type compressionPool struct {
+	sync.Pool
+	Level int
+}
+
+//  +------------------------------------------------------------+
+//  |                                                            |
+//  |                      GZIP                                  |
+//  |                                                            |
+//  +------------------------------------------------------------+
+
+// writes gzip compressed content to an underline io.Writer. It uses sync.Pool to reduce memory allocations.
+// Better performance through klauspost/compress package which provides us a gzip.Writer which is faster than Go standard's gzip package's writer.
+
+// These constants are copied from the standard flate package
+// available Compressors
+const (
+	NoCompressionLevel       = 0
+	BestSpeedLevel           = 1
+	BestCompressionLevel     = 9
+	DefaultCompressionLevel  = -1
+	ConstantCompressionLevel = -2 // Does only Huffman encoding
+)
+
+// default writer pool with Compressor's level setted to DefaultCompressionLevel
+var gzipPool = &compressionPool{Level: DefaultCompressionLevel}
+
+// AcquireGzipWriter prepares a gzip writer and returns it
+//
+// see ReleaseGzipWriter
+func acquireGzipWriter(w io.Writer) *gzip.Writer {
+	v := gzipPool.Get()
+	if v == nil {
+		gzipWriter, err := gzip.NewWriterLevel(w, gzipPool.Level)
+		if err != nil {
+			return nil
+		}
+		return gzipWriter
+	}
+	gzipWriter := v.(*gzip.Writer)
+	gzipWriter.Reset(w)
+	return gzipWriter
+}
+
+// ReleaseGzipWriter called when flush/close and put the gzip writer back to the pool
+//
+// see AcquireGzipWriter
+func releaseGzipWriter(gzipWriter *gzip.Writer) {
+	gzipWriter.Close()
+	gzipPool.Put(gzipWriter)
+}
+
+// WriteGzip writes a compressed form of p to the underlying io.Writer. The
+// compressed bytes are not necessarily flushed until the Writer is closed
+func writeGzip(w io.Writer, b []byte) (int, error) {
+	gzipWriter := acquireGzipWriter(w)
+	n, err := gzipWriter.Write(b)
+	releaseGzipWriter(gzipWriter)
+	return n, err
+}